Discontinuous reception

ABSTRACT

An interface of a terminal switches between at least one active state ( 283 ) and a sleep state ( 281 ) according to a schedule ( 200 ). Uplink control data is transmitted which is indicative of a temporary prolongation ( 209 ) of the at least one active state ( 283 ).

TECHNICAL FIELD

The invention generally relates to switching between at least one activestate and a sleep state of an interface of a terminal connectable to anetwork. The invention specifically relates to transmitting uplinkcontrol data which is indicative of a temporary prolongation of the atleast one active state.

BACKGROUND

In order to reduce power consumption of terminals that are connectableto a network, so-called Discontinuous Reception (DRX) is known. Forexample, according to Third Generation Partnership Project (3GPP) LongTerm Evolution (LTE) protocols, DRX can be implemented as described in3GPP Technical Specification (TS) 36.321 (Release 13.0.0), section 5.7for Radio Resource Control (RRC) connected mode and in 3GPP TS 36.304,section 7.1 for RRC idle mode.

According to 3GPP LTE DRX for connected mode (connected DRX), theterminal is ready to receive downlink (DL) payload data during an ONtime of the DRX cycle. An RRC connection is established at the beginningof the ON time and released at the end of the ON time. According to 3GPPLTE DRX for idle mode (idle DRX), the terminal is ready to receivenetwork paging during the ON time of the DRX cycle. An RRC connection isnot established during the ON time, but only established on demand ifthe terminal is in fact paged by the network. Both, in RRC connected andRRC idle, the UE may be registered with the network.

However, such techniques face certain restrictions and drawbacks. Forexample, it has been observed that implementing a comparably static DRXcycle can cause increased latency. Sometimes, DL payload data may not bedelivered in time to the terminal before the expiry of the ON time ofthe DRX cycle. Then, a comparably long time may lapse before the ON timeof the next repetition of the DRX cycle opens a new window ofopportunity for delivering the DL payload data. In particular, suchreference implementations impose certain constraints with respect to thedimensioning of the cycle length of the DRX cycle. For example, thecycle length of the DRX cycle is increased in an attempt to furtherreduce power consumption of terminals, the latency may further increase.

SUMMARY

Therefore, a need exists for advanced techniques of switching between atleast one active state and an sleep state according to a schedule. Inparticular, a need exists for such techniques which overcome or mitigateat least some of the above-identified restrictions and drawbacks.

This need is met by the features of the independent claims. Thedependent claims define embodiments.

According to an example, a terminal includes an interface. The interfaceis configured to communicate with the network on a wireless link. Theterminal further includes at least one processor. The at least oneprocessor is configured to control the interface to switch between atleast one active state and a sleep state according to a schedule. The atleast one processor is further configured to transmit uplink (UL)control data to the network. The UL control data is indicative of atemporary prolongation of the at least one active state.

According to an example, a method includes controlling an interface of aterminal to switch between at least one active state and a sleep stateaccording to a schedule. The method further includes transmitting ULcontrol data to a network. The UL control data is indicative of atemporary prolongation of the at least one active state.

According to an example, a computer program product includes programcode that may be executed by at least one processor. Executing theprogram code causes the at least one processor to perform a method. Themethod includes controlling an interface of a terminal to switch betweenat least one active state and a sleep state according to a schedule. Themethod further includes transmitting UL control data to a network. TheUL control data is indicative of a temporary prolongation of the atleast one active state.

According to an example, a computer program includes program code thatmay be executed by at least one processor. Executing the program codecauses the at least one processor to perform a method. The methodincludes controlling an interface of a terminal to switch between atleast one active state and a sleep state according to a schedule. Themethod further includes transmitting UL control data to a network. TheUL control data is indicative of a temporary prolongation of the atleast one active state.

According to an example, a network node of a network includes at leastone processor. The at least one processor is configured to receive ULcontrol data from the terminal. The UL control data is indicative of atemporary prolongation of at least one active state of a schedule. Theschedule is for switching an interface of the terminal between the atleast one active state and a sleep state. For example, the network nodemay be a base station.

According to an example, a method includes receiving UL control datafrom the terminal. The UL control data is indicative of a temporaryprolongation of at least one active state of a schedule. The schedule isfor switching an interface of the terminal between at least one activestate and a sleep state.

According to an example, a computer program product includes programcode that may be executed by at least one processor. Executing theprogram code causes the at least one processor to perform a method. Themethod includes receiving UL control data from the terminal. The ULcontrol data is indicative of a temporary prolongation of at least oneactive state of a schedule. The schedule is for switching an interfaceof the terminal between at least one active state and a sleep state.

According to an example, a computer program product includes programcode that may be executed by at least one processor. Executing theprogram code causes the at least one processor to perform a method. Themethod includes receiving UL control data from the terminal. The ULcontrol data is indicative of a temporary prolongation of at least oneactive state of a schedule. The schedule is for switching an interfaceof the terminal between at least one active state and a sleep state.

According to an example, a system includes a base station having atleast one processor. The system further includes a terminal having aninterface configured to communicate with a network node such as a basestation. The terminal further has at least one processor. The at leastone processor of the terminal is configured to control the interface ofthe terminal to switch between at least one active state and a sleepstate according to a schedule. The terminal and the network node arefurther configured to communicate UL control data indicative of atemporary prolongation of the at least one active state.

It is to be understood that the features mentioned above and featuresyet to be explained below can be used not only in the respectivecombinations indicated, but also in other combinations or in isolation,without departing from the scope of the present invention. Features ofthe above-mentioned aspects and embodiments may be combined with eachother in other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a cellular network including a basestation according to various examples, were in FIG. 1 furtherillustrates the terminal connectable to the network.

FIG. 2 schematically illustrates the terminal according to variousexamples.

FIG. 3 is a flowchart of a method according to various examples.

FIG. 4 schematically illustrates the base station according to variousexamples.

FIG. 5 is a flowchart of a method according to various examples.

FIG. 6 schematically illustrates a repetitive schedule for switching aninterface of the terminal between an active state in the sleep stateaccording to various examples.

FIG. 7 is a state diagram illustrating a connected state, an idle state,and a sleep state according to various examples.

FIG. 8 schematically illustrates a repetitive schedule for switching aninterface of the terminal between an active state and a sleep stateaccording to various examples.

FIG. 9A schematically illustrates a repetitive schedule for switching aninterface of the terminal between an active state and a sleep stateaccording to various examples.

FIG. 9B schematically illustrates a repetitive schedule for switching aninterface of the terminal between an active state and a sleep stateaccording to various examples.

FIG. 10 schematically illustrates a repetitive schedule for switching aninterface of the terminal between an active state and a sleep stateaccording to various examples.

FIG. 11 schematically illustrates a repetitive schedule for switching aninterface of the terminal between an active state and a sleep stateaccording to various examples.

FIG. 12 is a signaling diagram schematically illustrating thecommunication of UL control data indicative of a temporary deviationfrom a negotiated repetitive schedule according to various examples.

FIG. 13 is a signaling diagram schematically illustrating thecommunication of UL control data indicative of a temporary deviationfrom a negotiated repetitive schedule according to various examples.

FIG. 14 is a signaling diagram schematically illustrating thecommunication of UL control data indicative of a temporary deviationfrom a negotiated repetitive schedule according to various examples.

FIG. 15 is a signaling diagram schematically illustrating thecommunication of UL control data indicative of a temporary deviationfrom a negotiated repetitive schedule according to various examples.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the invention will be described indetail with reference to the accompanying drawings. It is to beunderstood that the following description of embodiments is not to betaken in a limiting sense. The scope of the invention is not intended tobe limited by the embodiments described hereinafter or by the drawings,which are taken to be illustrative only.

The drawings are to be regarded as being schematic representations andelements illustrated in the drawings are not necessarily shown to scale.Rather, the various elements are represented such that their functionand general purpose become apparent to a person skilled in the art. Anyconnection or coupling between functional blocks, devices, components,or other physical or functional units shown in the drawings or describedherein may also be implemented by an indirect connection or coupling. Acoupling between components may also be established over a wirelessconnection. Functional blocks may be implemented in hardware, firmware,software, or a combination thereof.

Hereinafter, techniques of switching between at least one active stateand a sleep state of an interface of a terminal are described.Sometimes, such techniques of switching between at least one activestate and an sleep state are referred to as DRX. By only activating anactive state of the interface every once in a while, power consumptionof the terminal can be reduced.

The switching may be implemented according to a schedule. For example,the schedule may be negotiated between the terminal and the network.Such negotiation of the schedule may involve UL control signaling and/orDL control signaling. Sometimes, the negotiation may take place as partof an attach procedure for establishing a data connection on a wirelesslink between the terminal and the network. In other examples, it wouldalso be possible that the schedule is predefined, e.g., according to afixed standard, etc.

The schedule may be repetitive, i.e., may define repetitions ofswitching between the different states. For example, the schedule may berepetitive in time domain: In some examples, it is possible that therepetitive schedule implements a periodicity for subsequent repetitions.It is also possible that the repetitive schedule is not strictlyperiodic, but shows a certain variation from repetition to repetition.The repetitions of the schedule are not required to be defined in timedomain; it would also be possible that the repetitions are defined inevent domain: For example, different repetitions of the schedule may beevent-triggered. An example of an event is the need for transmitting ULdata. A further example of an event is user activity or mobility of theterminal. In some examples, the repetitions may be defined in timedomain and event domain.

The schedule may indicate a timing for switching between the at leastone active state and the sleep state. This may facilitate DL datatransmission to the terminal, because the network then may be aware oftimes when the terminal is reachable.

For example, the schedule e.g., for each repetition may include acertain ON time during which one or more active states of the interfaceare activated. It may be possible to switch between different ones ofthe one or more active states during the ON time. Further, eachrepetition may include an OFF time during which a sleep state of theinterface is activated.

The interface may be fully or largely powered down when operating in thesleep state. Sometimes, the sleep state is also referred to as dormantstate or power safe state. For example, an analog front end of theinterface may be disabled during the sleep state. This may includepowering down one or more of the following: an analog amplifier; ananalog-to-digital converter. For example, a supply voltage may not beprovided to the analog amplifier and/or the analog-to-digital converterduring the sleep state. Generally, during the sleep state the interfacemay be unfit for receiving DL data on the wireless link. The terminalmay not send position updates in the sleep state. Thus, generally, inthe sleep state it may not be possible to send any DL data to theterminal. It is possible that during the sleep state the terminalremains registered in a respective repository of the network. All thisenables a low power consumption of the terminal in the sleep state.

Various active states are conceivable. Examples include a connectedstate. In the connected state, and ongoing data connection between theterminal and the network may be maintained. For example, the dataconnection may be implemented on the Network layer of the Open SystemsInterconnection (OSI) model according to the InternationalStandardization Organization (ISO) ITU-T X.200 (July 1994) document. Forexample, the data connection may include a bearer for identifying dataon an UL payload channel and/or a DL payload channel. The terminal maytransmit frequent position updates to the network in the connectedstate. For example, the serving cell at which the terminal presentlycamps may be known at any given moment in time to the network. In theconnected state, the interface of the terminal may be fully powered up.In the 3GPP LTE framework, an example is the RRC connected state.Typically, the connected state is associated with significant powerconsumption of the terminal.

A further example of an active state includes the idle state. Forexample, the idle state may be a mixture of the connected state and thesleep state. Because of this, sometimes, the idle state is also referredto as disconnected connected state. In the idle state, it may not berequired to maintain an ongoing data connection between the terminal andthe network. For example, in the idle state different to the connectedstate, the particular serving cell of a cellular network to which theterminal is connectable may not be known to the network. The terminalmay or may not transmit infrequent position updates, e.g., when changingthe tracking area, etc. For example, in the idle state it may bepossible for the network to page the terminal, i.e., to send a DL pagingto the terminal. However, it may not be possible to directly send DLpayload data. The DL paging may trigger the terminal to transition intothe connected state. This may involve performing an attach procedure forestablishing the payload channels of the wireless link. For example, inthe idle state, the analog front end of the interface of the terminalmay not be fully powered down, but generally functional. However,certain functions in the digital front end may be disabled which mayinclude limited demodulation/decoding functionality, etc. An example ofthe idle state in the 3GPP LTE framework is the RRC idle state. Anexample of the idle state is the RRC connected inactive state beingdiscussed in 3GPP for R14.

For example, the schedule may implement one or more active states incombination with the sleep state.

According to various examples, techniques are provided to temporarilydeviate from the schedule. In other words, techniques are providedaccording to various examples which enable to implement temporaryexceptions from the schedule. For example, such temporary deviationsfrom the schedule may include increasing or decreasing the ON time ofone or more repetitions. For example, such temporary deviations from theschedule may include increasing or decreasing the OFF time of one ormore repetitions of the schedule. For example, such temporary deviationsfrom the schedule may include increasing or decreasing a duration of arepetition of one or more repetitions of the schedule. Thus, variouspossibilities exist for configuring the temporary deviations. Forexample, such temporary prolongation may correspond to the prolongationof at least one active state defining the ON time. Thereby, it ispossible to dynamically tailor the schedule according to the temporaryrequirements of the terminal and/or the network.

According to various examples, the terminal may trigger such a deviationfrom the schedule. Then, the terminal may transmit uplink control datato the network which is indicative of the temporary deviation from theschedule envisioned by the terminal. Thereby, the network may beinformed accordingly to make use of any additional window of opportunityfor transmitting DL data or to avoid any DL transmission attempt whichis deemed to fail due to the temporary deviation.

For example, it may be possible that the temporary deviation isimplemented as a prolongation of the ON time, i.e., as a prolongation ofthe at least one active state. This may open an additional window ofopportunity for receiving DL data such as DL payload data.

One could consider a scenario where a service executed by the terminalis expecting DL payload data. This DL payload data may benetwork-initiated/terminal-terminating traffic.

For example, the DL payload data may be triggered by transmission of ULpayload data of the service. Due to the round-trip latency associatedwith the service e.g., a latency defined for communication from theterminal via the network to the server hosting the service and back viathe network to the terminal, the DL payload data may arrive at theterminal after expiry of the ON time. Then, the service executed by theterminal will not receive the DL payload data, because the interfacealready has entered the sleep state and is not reachable by the networkat that time. If the time duration until next ON time is large this mayimpose difficulties for the device communication with the server. Such ascenario may occur when the terminal is transmitting UL payload data toan Internet server where the Internet server provides a response to theterminal with a delay longer than the ON time. Other examples in whichsuch a scenario may occur include the terminal polling the serverhosting the service for update of certain configuration settings. Stillfurther examples in which a scenario may occur include the terminalpolling the server hosting the service for a firmware update.

Based on the techniques described herein, it may be possible toanticipate such a scenario where the DL payload data or arrives afterexpiry of the ON time and during the OFF time, i.e., at a point in timeat which the interface already switched back to the sleep state. Then,according to various examples described herein, it may be possible thatthe terminal transmits UL control data to the network, the UL controldata being indicative of the temporary deviation from the schedule. Forexample, if the at least one active state is prolonged, a window ofopportunity may be open for receiving the expected DL payload data.

FIG. 1 illustrates aspects with respect to the network 100. FIG. 1illustrates aspects with respect to the architecture of the network 100.The network 100 according to the example of FIG. 1 implements the 3GPPLTE architecture. According to 3GPP LTE, a wireless link 101 is definedin a RAN 114. The wireless link 101 is defined between a base station inthe form of an evolved node B (eNB) 112 and one or more UEs 130. Thewireless link 101 may implement one or more channels such as payloadchannels and/or control channels.

Furthermore, the network 100 includes a core network 113. The corenetwork 113 is in communication with the RAN 114. The core network 113includes a control layer and a data layer. The control layer includescontrol nodes such as the home subscriber server (HSS) 115, the mobilemanagement entity (MME) 116, and the policy and charging rules function(PCRF) 119. The data layer includes gateway nodes such as the servinggateway (SGW) 117 and the packet data network gateway (PGW) 118.

A data connection 160 is established between the UE 130-1 via the RAN114 and the data layer of the core network 113 and towards an accesspoint 121. For example, a connection with the Internet or another packetdata network can be established via the access point 121. A server ofthe packet data network or the Internet may host a service for whichpayload data is communicated via the data connection 160. The dataconnection 160 may include one or more bearers such as a dedicatedbearer or a default bearer. The data connection 160 may be defined onthe RRC layer. Establishing of the data connection 160 may thus includeOSI Network layer control signaling. By means of the data connection160, resources may be allocated on payload channels such as the PhysicalUplink Shared Channel (PUSCH) and/or the Physical Downlink SharedChannel (PDSCH).

The general functioning and purpose of the network nodes 115-119, 121 ofthe core network 113 is well known in the art such that a detaileddescription is not required in this context.

The illustration of the network 100 in the 3GPP LTE framework is forexemplary purposes only. Similar techniques can be readily applied tovarious kinds of 3GPP-specified architectures, such as Global Systemsfor Mobile Communications (GSM), Wideband Code Division Multiplex(WCDMA), General Packet Radio Service (GPRS), Enhanced Data Rates forGSM Evolution (EDGE), Enhanced GPRS (EGPRS), Universal MobileTelecommunications System (UMTS), and High Speed Packet Access (HSPA).For example, the techniques described herein may be applied to the 3GPPeNB-IoT or MTC systems or 3GPP New Radio (NR) systems. See, for example,3GPP RP-161321 and RP-161324. Furthermore, respective techniques may bereadily applied to various kinds of non-3GPP-specified networks, such asBluetooth, satellite networks, IEEE 802.11x Wi-Fi technology, etc.

FIG. 2 illustrates aspects with respect to the terminal 130. Theterminal 130 includes a processor 1301, e.g., a multi-core processor.The terminal 130 further includes a memory 1302, e.g., a non-volatilememory. The terminal 130 further includes an interface 1303.

The interface 1303 may include a digital front end and/or an analogfront end. The analog front end may be connectable to one or moreantennas. For example, the interface 1303 may include one or moreantenna ports. For example, the analog front end may include anamplifier such as a low noise amplifier and an analog-to-digitalconverter for receiving modulated and encoded signals. The analog frontend may include a digital-to-analog converter for transmission. Forexample, the digital front end when receiving data may be configured toperform tasks such as: demodulation; decoding; de-interleaving;calculation of checksums; etc. For example, the digital front end mayimplement lower level functionality according to the OSI model.Typically, such tasks as demodulation and decoding are also associatedwith considerable energy consumption.

The interface 1303 may operate according to different states ofoperation. These states may include one or more active states in whichthe interface 1303 is able to receive some or all DL data and/or signalstransmitted on the wireless link 101. For example, in the active states,the amplifier and/or the analog-to-digital converter may be at leastsometimes and/or at least partly provided with a supply voltage. Thesestates may further include a sleep state in which the interface 1303 isunfit to receive DL data transmitted on the wireless link 101.Typically, the power consumption of the terminal 130 is reduced if theinterface 1303 operates according to the sleep state if compared to theinterface 1303 operating according to one of the at least one activestates.

The memory 1302 may store control instructions that may be executed bythe processor 1301. Executing the control instructions can cause theprocessor 1301 to perform techniques of power saving; these may includecontrolling the interface 1303 to switch between at least one activestate and a sleep state according to a schedule.

FIG. 3 is a flowchart of a method according to various examples. Forexample, the method according to FIG. 3 may be executed by the processor1301 of the terminal 130.

First, in block 6001, the interface of the terminal is controlled toswitch between at least one active state and a sleep state. In someexamples, this may occur according to schedule. Generally, the schedulemay be known to the network. This may occur by negotiating the schedule.It would also be possible that the schedule is defined according tofixed rules. The schedule may be periodic. It is also possible that theschedule defines an event-triggered behavior. For example, the schedulecould define the ON duration after transmission of UL payload data.Here, the event triggering the ON duration would be the need fortransmitting the UL data. The schedule may be negotiated between theterminal and the network. For example, the method according to FIG. 3may further include negotiating the schedule between the terminal andthe network prior to block 6001.

Such switching according to block 6001 may implement a DRX cycle. Insome examples, according to the 3GPP LTE framework, the scheduleaccording to which switching is implemented at block 6001 may implementthe connected DRX and/or the idle DRX according to the 3GPP LTEframework. However, some examples described herein may go beyond the3GPP LTE DRX or provide alternative implementations. In some examples,the switching according to block 6001 may be event-triggered. Forexample, the ON duration could be activated in response to a need fortransmitting UL data.

Next, in block 6002, UL control data is transmitted to the network. TheUL control data is indicative of a temporary deviation from theschedule. In the example of FIG. 3, this is implemented as a temporaryprolongation of the at least one active state. For example in the aboveexample in response to the need for transmitting the UL data an extendedON duration can be indicated.

For example, the UL control data may be included in a dedicated controlmessage, e.g., a RRC layer control message. In further examples, it ispossible that the UL control data is piggybacked onto a control messageserving other purposes, e.g., a control message communicated during anattach procedure for establishing a data connection or a payloadchannel.

The temporary deviation from the schedule may correspond to aprolongation of the ON time. Thus, the temporary deviation maycorrespond to a prolongation of at least one active state of theinterface of the terminal. It is possible that the duration of theprolongation is also indicated by the UL control data; the duration mayalternatively be network-defined.

The method may further include implementing the temporary deviation fromthe schedule in response to transmitting the UL control data and block6002. Sometimes, the temporary deviation may be selectively implementeddepending on an acknowledgment of the network after transmitting the ULcontrol data.

The acknowledgment may be an explicit acknowledgment or an implicitacknowledgment. The acknowledgment may be a positive acknowledgment(PACK) or a negative acknowledgment (NACK). For example, if the networknegatively acknowledges the temporary deviation from the schedule,implementation of the temporary deviation may be suppressed. Forexample, if the network positively acknowledges the temporary deviationfrom the schedule, implementation of the temporary deviation may beexecuted. Respective DL control data which includes the acknowledgementmay, optionally, also include a duration of the deviation, e.g., aduration of a prolongation of the ON time.

FIG. 4 illustrates aspects with respect to the eNB 112. The eNB 112includes a processor 1121, e.g., a multi-core processor. The eNB 112further includes a memory 1122, e.g., a non-volatile memory. The eNB 112further includes an interface 1123. The interface 1123 may include adigital front end and/or an analog front end. The analog front end maybe connectable to one or more antennas. For example, the interface 1123may include one or more antenna ports. For example, the analog front endmay include an amplifier such as a low noise amplifier and ananalog-to-digital converter for receiving modulated and encoded signalson the wireless link 101.

The memory 1122 may store control instructions that may be executed bythe processor 1121. Executing the control instructions can cause theprocessor 1121 to perform techniques of power saving at a terminal 130connectable to the eNB 112. Such techniques may include synchronizingcommunication with the terminal 130 according to a schedule forswitching between at least one active state and a sleep state at theterminal. The schedule may be negotiated with the terminal.

FIG. 5 is a flowchart of a method according to various examples. Forexample, the method according to FIG. 5 may be executed by the processor1121 to perform techniques of power saving a terminal.

First, at block 6011, a schedule for switching, at the terminal, betweenat least one active state and a sleep state, is negotiated. Block 6011may include transmitting and/or receiving control data to and/or fromthe terminal. Block 6011 may be a one-way or a two-way negotiation.Block 6011 is optional. For example, instead of negotiating theschedule, the schedule may be fixedly predefined.

Next, at block 6012, UL control data is received from the terminal. TheUL control data is indicative of a temporary deviation from theschedule. In the example of FIG. 5, the temporary deviation is againimplemented as a prolongation of the at least one active state.

The method may further include implementing transmission of DL payloaddata and/or DL control data in accordance with the temporary deviationfrom the schedule.

For example, the method of FIG. 5 may be inter-related to the method ofFIG. 3. FIG. 6 schematically illustrates aspects with respect to arepetitive schedule 200. In FIG. 6, for illustrative purposes threerepetitions 231-233 of the schedule 200 are illustrated. However, theschedule 200 may include a larger number of repetitions 231-233 or asmaller number of repetitions 231-233.

Each repetition 231-233, according to the example of FIG. 6, includes anON time 201 and an OFF time 240. For example, in the repetition 231, aduration 211 of the ON time 201 is shorter than a duration 212 of theOFF time 240. The durations 211, 212 add up to the duration 213 of theentire repetition 231. While in the example of FIG. 6 a periodicity ofthe repetitions 231-233 is implemented, in other examples, differentrepetitions may have different durations.

In the ON time 201, the interface 1303 of the terminal 130 operates in aconnected state 283. In the OFF time 240, the interface 1303 of theterminal 130 operates in a sleep state 281. When operating in theconnected state 283 during the ON time 201, the interface 1303 is readyto receive DL data on the data connection 160. This is illustrated withrespect to the repetition 232 in the example of FIG. 6: here, DL payloaddata 261 is transmitted by the network 100 and accordance with theschedule 200; i.e., the DL payload data 261 arrives at the terminal 130during the ON time 201 when the interface 1303 operates in the connectedstate 283.

In the example of FIG. 6, reception of the DL payload data 261 triggersan inactivity timer 215. The inactivity timer 215 can also be triggeredby transmission of UL payload data 261. Also, other activity during theON time 201 can trigger the inactivity timer 215. The inactivity timer215 implements a prolongation 207 of the ON time 201 (illustrated by thedashed line in FIG. 6). This is according to the schedule 200, becauseit is a predefined behavior. The prolongation 207 opens an additionalwindow of opportunity for receiving further DL payload data while theinactivity timer 215 has not expired. The inactivity timer 215 is partof the schedule 200; as such, the network 100 is aware that due to theinactivity timer 215 another window of opportunity for transmitting DLpayload data is opened.

As will be appreciated from the above, it is not required that theschedule 200 defines a fully deterministic behavior. For example, theschedule 200 may define a set of rules for switching between thedifferent states and/or using timers and/or activating the ON time 201and the OFF time 240. However, these rules can take into account certainvariables such as the reception and/or transmission of data. Thus,depending on the circumstances, the behavior of the terminal 130 may notbe fully defined a-priori.

According to various examples described herein, it may be possible toimplement the temporary deviation from the schedule 200 bere-configuring a value of the inactivity timer 215, e.g., to a largervalue or a smaller value if compared to the schedule-defined value. Forexample, in response to transmitting the UL payload data 251 theinactivity timer 215 can then be triggered. Instead of using a fixedvalue for the inactivity timer 215, the re-configured value can beflexibly adjusted according to the needs of the service.

FIG. 7 schematically illustrates aspects with respect to various states281-283 in which the interface 1303 of the terminal 130 can operate.

In the example of FIG. 7, the sleep state 281 corresponds to a dormantstate of the interface 1303. Here, the terminal 130 is not fullydetached from the network 100, but still registered. Position updatesare not transmitted from the terminal 130 to the network 100. Thus, thenetwork 100 is unaware of a position of the terminal 130. Furthermore,one or more components of the interface 1303 may be powered down suchthat the interface 1303 is not able to receive DL data. The dataconnection 160 may not be established. Sometimes, in 3GPP LTE the sleepstate 281 is also referred to as power saving mode. See 3GPP TS 23.401V13.0.0 (2014 September), section 4.3.22 “UE Power Saving Mode”. Forexample, see 3GPP TS 23.682 V13.4.0 (2015 December).

In the further states 282, 283, the interface 1303 is generally ready toreceive DL data, e.g., at least during certain time slots and/or oncertain frequencies and/or according to certain coding/modulation. Thus,the states 282, 283 are sometimes referred to as active states (dashedline in FIG. 7).

In an RRC connected state 283, the terminal 130 maintains the dataconnection 160 with the network 100. See TS 36.331, chapter 4.2. Thismeans that handovers between different serving cells of the cellularnetwork 100 can be implemented without loss of the data connection 160.For this, the terminal 130 may transmit measurement reports on a qualityof communicating on the wireless link. The network 100 is aware of theserving cell. Differently, in the RRC idle state 282, the terminal 130may not maintain the data connection 160 with the network 100. Positionupdates may only be transmitted comparably infrequently or with a courseaccuracy, e.g., not defined on cell level. The interface 1303 may,nonetheless, be powered up at least to some degree. This may facilitatereceiving of DL paging signals from the network 100. The interface 1303may perform limited demodulation and decoding functionality. In responseto receiving a DL paging, the terminal 130 may transition into the RRCconnected state 283. For example, the power consumption of the interface1303 operating in the connected state 283 may be higher by at least 30%than a power consumption of the interface operating in the idle state282. Thus, while maintaining the terminal 130 and the active state, thepower consumption can still be reduced at the cost of latency introducedby the paging necessity.

For example, the transitions 288 from sleep state 281 to RRC connectedstate 283 or from RRC idle state 282 to RRC connected state 283 mayinvolve performing an attach procedure for establishing the dataconnection 160 including payload channels of the wireless link 101. Forexample, the attach procedure 288 may include a Random Access of theterminal 130 in which based on a randomly selected code and/or temporaryidentifications of the terminal 130 collision with further terminalsseeking to access the network 100 is mitigated. Typically, the RandomAccess is defined on a Physical layer according to the OSI model. Forexample, the attach procedure 288 may alternatively or additionallyinclude control signaling defined on a higher layer according to the OSImodel. Examples include an RRC attach procedure.

The transitions 289 from RRC connected state 283 to RRC idle state 282or from RRC connected state 283 to RRC sleep state 281 may include anRRC release procedure. In FIG. 7, furthermore, a transition 287 from theRRC idle state 282 to the RRC sleep state 281 is illustrated.

While in the example of FIG. 7, a number of two active states 282, 283has been illustrated, in further examples, it is possible that a largernumber of active states is provisioned. Some examples may include thePCH state, CELL_PCH State, URA_PCH State, CELL_FACH State, and CELL DCHState according to the 3GPP LTE TSs 25.331, section 7.1. Furthermore,while in the example of FIG. 7 the various states 281-283 have beenexplained with respect to the 3GPP LTE RRC layer functionality, in otherexamples, it is also possible to implement power-saving functionality ofthe interface 1303 on other layers and/or according to other protocolsbeyond 3GPP LTE. Nonetheless, various properties as explained above forthe states 281-283 in the context of 3GPP LTE RRC layer functionalitymay also be applied to other examples.

FIG. 8 illustrates aspects with respect to a repetitive schedule 200. Inparticular, FIG. 8 illustrates aspects with respect to implementing atemporary deviation from the schedule 200. The example of FIG. 8generally corresponds to the example of FIG. 6.

In the repetition 231, the terminal 130 transmits UL payload data 251 ofthe service. The service is associated with a certain round-trip latency260. The round-trip latency 260 is so long that the DL payload data 261associated with the UL payload data 251 of the service does not arriveduring the ON time 201. The DL payload data 261 arrives during the OFFtime 240. In the OFF time 240 the interface 1303 operates in the sleepstate 281. Therefore, the interface 1303 is unfit to receive data and,in particular, cannot receive the DL payload data 261 of the service.Then, reception of the DL payload data 261 is delayed until the next ONtime (not illustrated in FIG. 8 for sake of simplicity). This increaseslatency of the service.

In the repetition 232, a temporary deviation from the schedule 200 isimplemented. In particular, a prolongation 209 (illustrated by thedashed line in FIG. 8) is implemented. The prolongation 209 extends theON time 202. Thus, the prolongation 209 prolongs the active state 283 inthe repetition 232. This opens another window of opportunity forsuccessfully receiving the DL payload data 261.

FIG. 8 also illustrates a duration 219 of the prolongation 209. In maybe possible that the duration 219 is determined by logic residing at theterminal 130 and/or by logic residing in the network 100. In a simpleexample, the duration 219 may also be predefined. For example, theduration of the prolongation may be determined based on knowledge on theround-trip latency 260 of the service to which the payload data 251-261belongs to. For example, a-priori knowledge may be derived from previoustransmissions of payload data of the service. Thereby, it is possible totailor the duration 219 of the prolongation 209 such that excessiveincrease of the power consumption is avoided.

Generally, the duration 219 of the prolongation 209 may not be less than50% of the duration 211 of the ON time 202 during which the interface1303 operates in a active state 282, 283 according to the schedule 200.In some examples, the duration 219 may not be less than 200% of theduration 211, optionally lot less than 500%. Thereby, a significantwindow of opportunity can be open for receiving additional DL data. Onthe other hand, the duration 211 of the ON time 201 can be configured tobe normally short according to the schedule 200, thereby reducing theaverage power consumption.

On the other hand, the various techniques described herein facilitateconfiguration of a particularly long OFF time 240. By means of thetemporary prolongation 209, a likelihood for receiving the DL payloaddata 261 within the same repetition 231-233 in which the UL payload data251 is also transmitted can be increased. Thereby, it is possible toincrease the duration 212 of the OFF time 240. For example, the duration219 of the prolongation 209 may not be more than 10% of the duration212, optionally not more than 2%, further optionally not more than 0.1%.In absolute terms, the duration 212 may be on the order of minutes,hours or even days. In particular, in the context of IOT applications,this may facilitate reduced power consumption.

In the example of FIG. 8, the temporary deviation is restricted to thesingle repetition 232. Hence, a fallback to the schedule 200 isimplemented no later than in the repetition 233 which is adjacent andsubsequent to the repetition 232. By restricting the temporary deviationto a single repetition, the power-consumption optimized schedule 200 canbe largely implemented with the exception of those repetitions in whicha need for receiving the DL payload data is detected. In other examples,the temporary deviation may also cover more than a single repetition.

FIG. 9A illustrates aspects with respect to a repetitive schedule 200.In particular, FIG. 9A illustrates aspects with respect to implementinga temporary deviation from the schedule 200. The example of FIG. 9Agenerally corresponds to the example of FIG. 8.

In the example of FIG. 9A, again, in the repetition 232 of the schedule200, the prolongation 209 as deviation from the schedule 200 isimplemented. Here, the interface 1303 operates in the idle state 282during the prolongation 209. Thus, upon expiry of the ON time 202—inwhich the interface 1303 operates in the connected state at 283—, theinterface 1303 switches the mode of operation and then continues tooperate in the idle state 282. This may include releasing the dataconnection 160 which has been established during the ON time 202 andlistening for DL paging signals in the idle state 282. The DL pagingsignals can then help to trigger another attach procedure 288 once theDL payload data 261 is ready for transmission at the eNB 112 (notillustrated in FIG. 9A for sake of simplicity). By implementing twoactive states 283, 282 according to the example of FIG. 9A, the powerconsumption of the terminal 130 can be reduced while still opening afurther window of opportunity for receiving the DL payload data 261.

FIG. 9B illustrates aspects with respect to a repetitive schedule 200.In particular, FIG. 9B illustrates aspects with respect to implementinga temporary deviation from the schedule 200. The example of FIG. 9Bgenerally corresponds to the example of FIG. 9A. Here, after receivingthe downlink payload data 261, the inactivity timer 215 is triggered.

FIG. 10 illustrates aspects with respect to a repetitive schedule 200.In particular, FIG. 10 illustrates aspects with respect to implementinga temporary deviation from the schedule 200. The example of FIG. 10generally corresponds to the example of FIG. 9A.

In the example of FIG. 10, again, in the repetition 232 of the schedule200, the prolongation 209 as deviation from the schedule 200 isimplemented. Here, the interface 1303 operates in the idle state 282during the prolongation 209. In the example of FIG. 10, a fallback tothe schedule 200 is implemented in response to receiving the DL payloaddata 261. This means that after receiving the DL payload data261—instead of proceeding to operate in the idle state 282 for a certainduration—, the interface 1303 directly switches back to operating in thesleep state 240. This helps to further reduce the power consumption ofthe terminal 130. Such a scenario could also be employed for a schedule200 according to other examples, e.g., the example of FIG. 8.

FIG. 11 illustrates aspects with respect to a repetitive schedule 200.In particular, FIG. 11 illustrates aspects with respect implementing atemporary deviation from the schedule 200. The example of FIG. 11generally corresponds to the example of FIG. 8.

In the example of FIG. 11, the prolongation 209 is not triggered by theend of the ON time 202. Rather, a timer is initialized based on thedetermined duration 219 of the prolongation 209 in response totransmitting the UL payload data 251. Thereby, an accurate measure withrespect to the expected round-trip latency 260 can be implemented.Excessive power consumption of the terminal 130 may be avoided.

The various examples described in FIGS. 8-11 can be combined with eachother in further examples. For example, the timer techniques of FIG. 11may be combined with the idle state techniques of FIGS. 9 and 10.

As will be appreciated from the above, it may be possible to implementthe techniques of switching between the different states 281-283according to a DRX cycle, e.g., in the 3GPP LTE framework. Here,connected DRX and/or idle DRX can be used in order to implement thetechniques of switching between the different states 281-283. Forexample, the prolongation 209 may be implemented by temporarilyreconfiguring the inactivity timer of DRX. The inactivity timer mayspecify a time duration during which the interface 1303 is controlled tocontinue operation in the at least one active state 282, 283 whenexpecting the DL payload data 261. For example, the inactivity timer maybe triggered in response to transmitting UL payload data 251 and/or inresponse to receiving DL payload data.

FIG. 12 is a signaling diagram illustrating aspects with respect tosignaling UL control data 300 indicative of a temporary deviation from arepetitive schedule 200. FIG. 12 further illustrates aspects withrespect to switching between the different states 281, 283.

Initially, the interface 1303 of the terminal 130 operates in the sleepstate 281. Then, according to the schedule 200, the interface 1303switches to the connected state 283. This includes performing an attachprocedure 288 for establishing a DL payload channel and an UL payloadchannel. The attach procedure 288 may include a Random Access (notillustrated in FIG. 12). The attach procedure 288 also includes theterminal 130 transmitting an RRC Connection Request message 8001. TheRRC Connection Request message 8001 seeks to establish an RRC connectionsuch as the data connection 160. Then, the eNB 112 response with the RRCConnection Response message 8002. This facilitates establishing of thedata connection 160. As can be seen from FIG. 12, the transition intothe connected state 283 involves communicating of RRC layer controlmessages to configure the connected state 283. Thus, the connected state283 may be generally defined on the OSI Network layer level.

Next, the terminal 130 transmits a UL control message 8003. The ULcontrol message 8003 includes the UL control data 300. The UL controldata 300 is indicative of a temporary prolongation 209 as deviation fromthe schedule 200 for the active repetition.

The terminal 130 also transmits a message 8004 including the UL payloaddata 251. Then, in conformity with the UL control data 300, the terminal130 implements the temporary prolongation 209 of the connected state283. During the prolongation 209, the terminal 130 receives, from thenetwork 100 and in particular from the eNB 112, a message 8005 whichincludes the DL payload data 261. The DL payload data 261 and the ULpayload data 251 belong to the same service. It is possible that the DLpayload data 261 originates from the same server to which the UL payloaddata 251 is addressed, e.g., on TCP/IP level or Transport layeraccording to the OSI model.

Then, upon expiry of the prolongation 209, and RRC Connection releasemessage 8006 is transmitted from the network 100 to the terminal 130.The message 8006 facilitates transition 289 into the sleep state 281.The data connection 160 is released. This configures the sleep state281.

FIG. 13 is a signaling diagram illustrating aspects with respect tosignaling UL control data 300 indicative of a temporary deviation from arepetitive schedule 200. FIG. 13 further illustrates aspects withrespect to switching between the different states 281, 282, 283.

8011-8014 generally correspond to 8001-8004. Then, an RRC ConnectionRelease message 8015 is transmitted from the network 100 to the terminal130. This facilitates transition from the connected state 283 into theidle state 282. In particular, the data connection 160 is released.Then, the terminal 130 receives a DL paging 8016 during the prolongation209. In response to the receiving of the DL paging 8016, the attachprocedure 288 is performed which again includes communication of the RRCConnection Request message 8017 and a RRC Connection Response message8018. The messages 8017, 8018 facilitate establishment of the dataconnection 160. Then, via the data connection 160, a message 8019including the DL payload data 261 can be received.

At the end of the prolongation 209, and RRC Connection Release message8020 is communicated in order to release the data connection 160 andtransition into the sleep state 281.

In the examples of FIGS. 12 and 13, the control data 300 is transmittedas part of a control message 8003, 8013 transmitted after completion ofthe attach procedure 288. For example, the control messages 8003, 8013can be dedicated control messages transmitted on a control channel suchas the physical UL control channel (PUCCH) in the 3GPP LTE framework.Other examples of transmitting the control data 300 are possible. Forexample, the control data 300 may be transmitted as part of the attachprocedure.

FIG. 14 is a signaling diagram illustrating aspects with respect tosignaling UL control data 300 indicative of a temporary deviation from arepetitive schedule 200. FIG. 14 further illustrates aspects withrespect to switching between the different states 281, 283. FIG. 14further illustrates aspects with respect to piggybacking the UL controldata onto a control message.

The example of FIG. 14 generally corresponds to the example of FIG. 12.However, in the example of FIG. 14, the control data 300 indicative ofthe deviation from the schedule 200, in particular indicative of theprolongation 200, is piggybacked onto the RRC Connection Request message8031 communicated during the attach procedure 288. It would also bepossible that the control data 300 is piggybacked onto a differentcontrol message communicated the attach procedure 288. Thus, accordingto the example of FIG. 14, the UL control data 300 is transmitted duringthe attach procedure 288. This helps to inform the network 100 withsufficiently time of the prolongation 209. Further, control signalingoverhead may be reduced. The example of FIG. 14 may be combined, e.g,with the example of FIG. 13, etc.

8032-8035 generally correspond to 8002, 8004-8006.

Generally, the control data 300 may be a single bit information field.Then, the deviation from the schedule 200 can be implemented accordingto predefined rules. In further examples, it would also be possible thatthe control data 300 includes multi-bit information. For example, thecontrol data 300 may be indicative of a duration of the temporarydeviation, e.g., indicative of the duration 219 of the prolongation 209.Then, the terminal 130 may flexibly decide—e.g., based on theanticipated power consumption and/or the round-trip latency of theservice associated with the payload data 251, 261—what duration of thetemporary deviation is appropriate in the given circumstances. In otherexamples, it may also be possible that the duration of the temporarydeviation is network-defined. For example, corresponding logic mayreside in the eNB 112. In such a scenario, it may be possible toconsider further factors such as transmission collision between multipleterminals etc. For example, the UL control data 300 may be indicative ofthe service. Then, the network 100 may have additional a-prioriknowledge on the typical round-trip latency associated with thatservice. For example, the eNB 112 may monitor the round-trip latency.Further, the network may take into consideration scheduling constraintsfor transmitting the DL payload data 261. This may increase an accuracyof dimensioning the duration of the temporary deviation. For example, DLcontrol data may be transmitted from the network 100 to the terminal130, the DL control data being indicative of a duration of the temporarydeviation from the schedule 200 (not shown in FIG. 14), e.g., inmultiples of a default duration.

By means of the control data 300, the network 100 is made aware of thedeviation from the schedule 200. Then, the eNB 112 may transmit the DLpayload data 261 according to the deviation in order to facilitatetimely reception thereof.

FIG. 15 is a signaling diagram illustrating aspects with respect tosignaling UL control data 300 indicative of a temporary deviation from arepetitive schedule 200. FIG. 15 further illustrates aspects withrespect to switching between the different states 281, 283. FIG. 15further illustrates aspects with respect to communicating a downlinkacknowledgement from the network 100 to the terminal 130.

The example of FIG. 15 generally corresponds to the example of FIG. 12.For example, 8041-8043 correspond to 8001-8003. In the example of FIG.15, the network 100 sends a DL control message 8044. The control message8044 is indicative of an acknowledgment 310 of the UL control data 300which has been previously communicated as part of the control message8043.

In the example of FIG. 15, the network 100 positively acknowledges thetemporary prolongation 209 as deviation from the schedule 200, i.e.,sends a positive acknowledgement (PACK) sometimes the PACK is simplyreferred to as ACK. Because of this acknowledgment 310, the terminal 130proceeds and implements the prolongation 209. For example, if a negativeacknowledgment (NACK) was received by the terminal 130 (not illustratedin FIG. 15), the terminal 130 could continue according to the predefinedschedule 200, i.e., skipping the prolongation 209.

Generally, a transmission of an acknowledgment is not mandatory. Thetransmission of an acknowledgment by the network is optionally. Forexample, if a technique without explicit downlink control signaling isimplemented, it would be possible to implicitly acknowledge the requestof the terminal. Acknowledgement techniques may also be employed in theother examples described herein, e.g., in the examples of FIGS. 12-14.

For example, in response to transmitting the UL control data, theterminal 130 may receive an acknowledgment. It would be possible thatthe UL control data is not indicative of a duration of the prolongation209. Then, the predefined value for the duration of the prolongation 209could be used. For example, such a predefined value could use astandardized multiple of a preconfigured default timer value. Forexample, it would also be possible that the UL control data isindicative of the duration of the prolongation 209. Then, if theacknowledgment positively acknowledges such a request made by theterminal 130, the indicated duration of the prolongation 209 may beused. However, if the acknowledgment negatively acknowledges such arequest made by the terminal 130, a default value can be used for theduration 219 of the prolongation 209.

In further examples, the DL control data can include the acknowledgmentand possibly a response parameter. For example, the terminal receives apositive acknowledgment including a response parameter, this parametermay define the duration 219 of the prolongation 209, e.g., as amultiplier of an earlier configured default value. For example, theterminal receives a negative acknowledgment, a default value can beused.

8045-8047 then correspond to 8004-8006.

Although the invention has been shown and described with respect tocertain preferred embodiments, equivalents and modifications will occurto others skilled in the art upon the reading and understanding of thespecification. The present invention includes all such equivalents andmodifications and is limited only by the scope of the appended claims.

While above various examples have been described with respect to Networklayer-defined states of the interface, similar examples may be alsoemployed with respect to states of the interface that are defined on thelayers such as the physical layer (layer 1) and/or the data link layer(layer 2).

While above various examples have been described with respect to atemporary prolongation, similar techniques could also be applied withrespect to other kinds of temporary deviations from the negotiatedschedule, e.g., temporary shortenings of the at least one active stateor temporary extensions of the duration of the repetition, etc.

While above various examples have been described with respect to aperiodic schedule, respective techniques may be readily applied for anevent-triggered schedule. For example, an ON-time may be triggered inresponse to a need of transmitting UL data.

For example, while various examples have been described with respect toan inactivity timer which is triggered upon reception of DL data,similar techniques may be readily implemented when triggering theinactivity timer alternatively or additionally upon transmission of ULdata.

The invention claimed is:
 1. A terminal, comprising: an interfaceconfigured to communicate with a network on a wireless link, and atleast one processor configured to control the interface to switchbetween at least one active state and a sleep state according to aschedule, the at least one active state comprising a connected statewhere the terminal maintains a data connection on a wireless link withthe network, the data connection being released during the sleep state,wherein the at least one processor is configured to transmit uplinkcontrol data to the network indicative of a temporary prolongation ofthe at least one active state, the uplink control data being piqqybackedonto a control message communicated during a procedure for establishingthe data connection.
 2. The terminal of claim 1, wherein the schedule isrepetitive, wherein the at least one processor is configured to transmitthe uplink control data in a given repetition of the schedule, theuplink control data being indicative of the prolongation of the at leastone active state in the given repetition.
 3. The terminal of claim 2,wherein the at least one processor is configured to transmit, via theinterface, uplink payload data of a service in the given repetition ofthe schedule, wherein the at least one processor is configured toreceive, via the interface, downlink payload data of the service in thegiven repetition of the schedule and during the prolongation, whereinthe at least one processor is configured to determine a duration of theprolongation based on knowledge on a roundtrip latency of the service.4. The terminal of claim 3, wherein the at least one processor isconfigured to receive, via the interface, a downlink paging signal inthe given repetition of the schedule and during the prolongation,wherein the at least one processor is configured to perform an attachprocedure for establishing a data connection on the wireless link inresponse to said receiving of the downlink paging signal, wherein the atleast one processor is configured to receive the downlink payload dataon the data connection.
 5. The terminal of claim 3, wherein the at leastone processor is configured to initialize a timer based on thedetermined duration of the prolongation and in response to transmittingthe uplink payload data.
 6. The terminal of claim 3, wherein the atleast one processor is configured to fall back to the schedule inresponse to receiving the downlink payload data.
 7. The terminal ofclaim 2, wherein the at least one processor is configured to control theinterface to operate in a connected state selected from the at least oneactive state in the given repetition and prior to the prolongation, theinterface being configured to maintain a data connection of the wirelesslink in the connected state, wherein the at least one processor isconfigured to control the interface to operate in an idle state selectedfrom the at least one active state in the given repetition of theschedule during the prolongation, the interface being configured torelease the data connection and to listen for downlink paging signal inthe idle state.
 8. The terminal of claim 2, wherein a duration of theprolongation is not less than 50% of a duration of the at least oneactive state according to the schedule, optionally not less than 200%,further optionally not less than 500%, and/or wherein the duration ofthe prolongation is a fraction of the duration of the sleep state. 9.The terminal of claim 1, wherein the schedule implements a DiscontinuousReception (DRX) cycle, wherein the prolongation is implemented bytemporarily reconfiguring an inactivity timer of the DRX cycle, theinactivity timer defining a time duration during which the interface iscontrolled to continue operation in the at least one active state whenexpecting downlink payload data.
 10. The terminal of claim 1, whereinthe uplink control data is indicative of a duration of the temporaryprolongation.
 11. The terminal of claim 1, wherein the at least oneprocessor is configured to receive downlink control data indicative ofan acknowledgement of the uplink control data, wherein the at least oneprocessor is configured to selectively implement the temporaryprolongation based on the acknowledgement.
 12. The terminal of claim 11,wherein the downlink control data is further indicative of a duration ofthe temporary prolongation.
 13. The terminal of claim 1, wherein theschedule is repetitive, wherein the at least one processor is configuredto implement the temporary prolongation in a first repetition of theschedule, wherein the at least one processor is configured to fall backto the schedule no later than in a second repetition of the schedule,the second repetition being adjacent and subsequent to the firstrepetition.
 14. The terminal of claim 1, wherein the at least oneprocessor is configured to selectively trigger the temporaryprolongation in response to a need for receiving downlink payload dataof a service, wherein the at least one processor is configured toreceive the downlink payload data during the prolongation.
 15. Theterminal of claim 1, wherein the schedule is negotiated with network oris predefined.
 16. A system, comprising: a network node having at leastone processor, and a terminal according to claim
 1. 17. A network nodeof a network, comprising: at least one processor configured to receiveuplink control data from a terminal indicative of a temporaryprolongation of at least one active state of a schedule for switching aninterface of the terminal between at least one active state and a sleepstate, wherein the at least one active state comprises a connected statewhere the terminal maintains a data connection on a wireless link withthe network, the data connection being released during the sleep state,and the uplink control data being piggybacked onto a control messagecommunicated during a procedure for establishing the data connection.18. A method, comprising: controlling an interface of a terminalconnected to a network to switch between at least one active state and asleep state according to a schedule, the at least one active statecomprising a connected state where the terminal maintains a dataconnection on a wireless link with the network, the data connectionbeing released during the sleep state, and transmitting, to the network,uplink control data indicative of a temporary prolongation of the atleast one active state, the uplink control data being piggybacked onto acontrol message communicated during a procedure for establishing thedata connection.
 19. A method, comprising: receiving uplink control datafrom a terminal, the uplink control data being indicative of a temporaryprolongation of at least one active state of a schedule for switching aninterface of the terminal between at least one active state and a sleepstate, wherein the at least one active state comprises a connected statewhere the terminal maintains a data connection on a wireless link withthe network, the data connection being released during the sleep state,and the uplink control data being piggybacked onto a control messagecommunicated during a procedure for establishing the data connection.